A computer program for simulating time travel and a possible solution for the grandfather paradox

📝 Abstract

While the possibility of time travel in physics is still debated, the explosive growth of virtual-reality simulations opens up new possibilities to rigorously explore such time travel and its consequences in the digital domain. Here we provide a computational model of time travel and a computer program that allows exploring digital time travel. In order to explain our method we formalize a simplified version of the famous grandfather paradox, show how the system can allow the participant to go back in time, try to kill their ancestors before they were born, and experience the consequences. The system has even come up with scenarios that can be considered consistent “solutions” of the grandfather paradox. We discuss the conditions for digital time travel, which indicate that it has a large number of practical applications.

💡 Analysis

While the possibility of time travel in physics is still debated, the explosive growth of virtual-reality simulations opens up new possibilities to rigorously explore such time travel and its consequences in the digital domain. Here we provide a computational model of time travel and a computer program that allows exploring digital time travel. In order to explain our method we formalize a simplified version of the famous grandfather paradox, show how the system can allow the participant to go back in time, try to kill their ancestors before they were born, and experience the consequences. The system has even come up with scenarios that can be considered consistent “solutions” of the grandfather paradox. We discuss the conditions for digital time travel, which indicate that it has a large number of practical applications.

📄 Content

1

A computer program for simulating time travel and a possible ‘solution’ for the grandfather paradox Doron Friedman, The Interdisciplinary Center, Herzliya, Israel doronf@idc.ac.il Abstract While the possibility of time travel in physics is still debated, the explosive growth of virtual-reality simulations opens up new possibilities to rigorously explore such time travel and its consequences in the digital domain. Here we provide a computational model of time travel and a computer program that allows exploring digital time travel. In order to explain our method we formalize a simplified version of the famous grandfather paradox, show how the system can allow the participant to go back in time, try to kill their ancestors before they were born, and experience the consequences. The system has even come up with scenarios that can be considered consistent “solutions” of the grandfather paradox. We discuss the conditions for digital time travel, which indicate that it has a large number of practical applications.

1. Introduction In the principal paradox of time travel a person travels back in time and kills his grandfather before the grandfather meets the time traveler’s grandmother. As a consequence, one of the traveler’s parents, and therefore the traveler himself, would never have been born. This would imply that the traveller could not have travelled back in time, which means that the grandfather would still be alive, which now makes it possible for the traveler to be born, travel back in time and kill his grandfather, hence a paradox.
   In this paper we describe a computer program that allows us to interactively explore the consequences of “changing the past” in a narrative. Our system uses well-known techniques from automated reasoning to compute the specific consequences of modifying history. The contribution of this paper is in the application of automated reasoning to the experience of time travel and in the implementation of this method in a computer 2

program. We provide the details showing how our program was used to interactively explore the consequences of time travel while maintaining consistency in the context of a simplified version of the grandfather paradox. Furthermore, we show how the program was used to proactively resolve the paradox by suggesting transformations of the story line, resulting in some narratives that may be considered valid solutions to the famous paradox. We explain the difference between our time travel approach and other types of digital simulations. Finally, we explicate the conditions required for digital time travel, which indicate that the method can be applied in many useful domains.
Time travel is discussed in physics, philosophy, and popular culture. In this paper we deliberately avoid the discussion of time travel in physics, and try to capture the notions of time, causality, and time travel as they are perceived by laymen, assisted by insights provided by analytic philosophers. An early discussion of time travel in philosophy in contemporary times has been provided by Lewis (Lewis 1976). His suggestion for resolving the paradox rests on the hypothesis that if time travel is possible then some mundane event will always happen to prevent paradoxes from taking place. Horwich (Horwich 1975) criticized this view by pointing out that if travel to the local past is allowed then there would be countless attempts to initiate self-defeating causal chains, and it would be highly improbable that all of them would be avoided by mundane events such as slipping over a banana peel. Further investigations of time travel in philosophy lead to discussions of causality, identity, and other metaphysical issues (Dowe 2000, Grey 1999, Smith 1997). Our goal in this computer program is to borrow from these discussion and provide a virtual time travel experience that would be consistent with some popular notions of time travel. Nevertheless, we hope that future work based on our formalization of time travel in a computer program may contribute to the philosophical discussion.
Unlike the physical world, the digital sphere allows you to “go back in time”, make a change, and observe the consequences. This can be as simple as the “undo” function in a word-processing program, or take place in the context of a rich experience such as in a virtual-reality simulation. For example, consider a video game in which you can be upset at the way things turned out at time t, restart the game and continue playing from a 3

previous time t’, t’ < t. Typically, in such cases whatever happened between t’ and t is lost forever, and the simulation restarts. Our approach is different; it allows the participant to re-experience the history that took place between t’ and t. The history will be repeated, except for local changes caused by the participant’s actions in the “second time around”. The difference between our approach and typical

This content is AI-processed based on ArXiv data.